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Finding the Fourth Proportional to 809.92, 1,215.99 and 420.24

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Solution

The fourth proportional to 809.92, 1,215.99 and 420.24 is: 630.94

Step by Step Solution

  1. Step 1: Write the proportion equation
    809.92 : 1,215.99 = 420.24 : x
  2. Step 2: Convert to fraction form
    809.92/1,215.99 = 420.24/x
  3. Step 3: Cross multiply
    809.92x = 1,215.99 × 420.24
  4. Step 4: Simplify right side
    809.92x = 511,007.64
  5. Step 5: Solve for x
    x = 511,007.64/809.92
  6. Step 6: Final answer
    x = 630.94

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.